Identification of genes causing human genetic diseases will lead to new methods of diagnosis and treatment of many disorders. The screening of candidate genes for mutations is rapidly becoming the rate-limiting step in the disease gene identification process (positional cloning). Thus, new methods for mutation detection are needed. In addition, new cost efficient methods for high throughput genotyping are needed for screening populations for genetic risk factors, for studies to identify polygenic disease loci, and for more efficient linkage analysis of single g,ene disorders. The goals of this project are to evaluate and develop methods for identifying mutations in DNA and to develop methods and resources necessary for high throughput genotyping. To achieve these goals, we will determine factors currently limiting the sensitivity of single strand conformation polymorphism (SSCP) analysis for detection of single base changes, and seek to improve the sensitivity of this technique by modification of gel matrices, electrophoresis conditions, and the nucleotide composition of the DNA sample to be analyzed. In addition, new mutation detection methods will be developed by taking advantage of mismatch binding proteins and endonucleases. Finally, cost effective strategies and reagents for high throughput genotyping will be developed using tetranucleotide repeat polymorphic markers.